Craniofacial related birth defects account for 1/3rd of all congenital anomalies. Defects in neural crest cells (NCC) cause most of these disorders;however, the signaling pathways involved in craniofacial morphogenesis are poorly understood. Therefore, knowledge of the molecular mechanisms of neural crest development is necessary to understand human craniofacial disorders. Our long-term goal is to identify the regulatory pathways that instruct NCC morphogenesis. The objective of this application is to determine the molecular and genetic role of the TFII-I transcription factor in craniofacial development. Deletion of the Gtf2i allele, which encodes this protein causes craniofacial defects in mice. TFII-I regulates the transcription of target genes via interactions with histone deacetylases and Smad2 and is expressed in neural crest-derived tissues. We hypothesize that 1 of the roles of TFII-I is to control signaling cascades critical for neural crest morphogenesis. We, therefore, propose an in depth analysis of Gtf2i to understand its role during neural crest development. First, molecular and cellular changes underlying craniofacial defects will be analyzed in mutant embryos. Second, a set of downstream target genes regulated by TFII-I in cranial NCC will be identified using microarray and chromatin immunoprecipitation analysis. Third, the Gtf2i allele will be abrogated in the NCC lineage with the conditional Cre/LoxP recombination system. The outcome of the proposed research will allow us to identify the TFII-l-dependent genes and signaling pathways involved in the morphogenesis of neural crest-derived structures. These studies will provide a better understanding of craniofacial genetic pathways and pathogenesis of human birth defects.